Conductor sizing in cord connected load

[GeorgeB]

We are supplying a small portable (wheels) hydraulic power unit (5HP, 460-3-60) to a customer who asked us to furnish a 40 foot long power cable for them to plug it into their plant welding receptacles. Our electrical equipment is a simple combination starter including control transformer for over temperature and under level switches in a 120 control circuit. We are NOT a UL approved facility. We don't consider this (perhaps wrongly) a "control panel".

These "welding" convenience receptacles are protected and wired for 60A and use a pin-sleeve dead connect system. They will put their plug on our cable.

At the 6.1A full load, and for cord coiling and storage convenience, I would not usually use a cable suitable for 60A. From purely an ampacity standpoint, 16AWG would be suitable ... we'd usually furnish 14AWG and a L16-20P expecting a matching receptacle.

I am puzzled by requirements here ... I can plug #18 lamp cords into a 20A receptacle at the desk, but ...

It's not the cost of the wire, it is the convenience ... SHOULD we furnish 6AWG SO cord? Or SHOULD we furnish something in between? What are the criteria?

 

[kwired]

If they are putting their plug on your supplied cord then I think anything that is wrong with that is not your problem.

You could put 60 amp cord on it. It should also have overcurrent protection suitable for the load within the control panel.

 

[iwire]

IMO you cannot plug a 20 amp cord into a 50 - 60 amp circuit.

 

[Electroplaxes]

I am puzzled by requirements here ... I can plug #18 lamp cords into a 20A receptacle at the desk, but ...

Look at 240.5

 

[petersonra]

We are supplying a small portable (wheels) hydraulic power unit (5HP, 460-3-60) to a customer who asked us to furnish a 40 foot long power cable for them to plug it into their plant welding receptacles. Our electrical equipment is a simple combination starter including control transformer for over temperature and under level switches in a 120 control circuit. We are NOT a UL approved facility. We don't consider this (perhaps wrongly) a "control panel".

These "welding" convenience receptacles are protected and wired for 60A and use a pin-sleeve dead connect system. They will put their plug on our cable.

At the 6.1A full load, and for cord coiling and storage convenience, I would not usually use a cable suitable for 60A. From purely an ampacity standpoint, 16AWG would be suitable ... we'd usually furnish 14AWG and a L16-20P expecting a matching receptacle.

I am puzzled by requirements here ... I can plug #18 lamp cords into a 20A receptacle at the desk, but ...

It's not the cost of the wire, it is the convenience ... SHOULD we furnish 6AWG SO cord? Or SHOULD we furnish something in between? What are the criteria?

IMO, this is indeed a control panel . Look at the definition of control panel in the NEC (409.2).

UL seems to think anything with wires in it that does not fit any other existing classification can be listed under UL508a.

How is a #14 cord protected by a 60A OCPD? The answer is that it is not. Why not just use some inline 15A fuses.

 

[GeorgeB]

Thanks folks.

How is a #14 cord protected by a 60A OCPD? The answer is that it is not.

I agree with you and everyone else ... including it being a control panel by definition. It itself will be UL listed ... technically when we add the series devices in the control circuit I THINK we violate the listing.

Why not just use some inline 15A fuses.

I'm ignorant of any such thing. The only way I can picture that would be an enclosure with fuse blocks fed with large wire then our (what, now 35') tail of smaller wire. Easier to handle the coil of 6AWG. Fuses in the plug would be nice ...

The combination starter that is used has either fuses or a MCP for overcurrent protection ... and a "proper" overload block.

 

[kwired]

Thanks folks.

I agree with you and everyone else ... including it being a control panel by definition. It itself will be UL listed ... technically when we add the series devices in the control circuit I THINK we violate the listing.I'm ignorant of any such thing. The only way I can picture that would be an enclosure with fuse blocks fed with large wire then our (what, now 35') tail of smaller wire. Easier to handle the coil of 6AWG. Fuses in the plug would be nice ...

The combination starter that is used has either fuses or a MCP for overcurrent protection ... and a "proper" overload block.

T400.5(A) says you need a 4 AWG cord. At 35-40 feet that is a heavy cord compared to the 16 AWG cord you would otherwise be allowed to use, but it will certainly work.

One solution depending on what it takes, could be to tap the 60 amp circuit with proper OC devices and then install the L16-20 receptacle you said you would normally put on the supply cord, or put 60 amp plug on a short 4 AWG cord, supply a receptacle and overcurrent device(s) on a separate stand alone frame of some kind and plug your machine into that.